The purposes of this study are to evaluate the toxicity of an investigational agent (IL-6), a growth promoting factor, and the antitumor effectiveness of the combination of drugs Ifosfamide, Carboplatin, and Etoposide in terms of beneficial effects in tumor reduction and long-term disease-free survival, and to investigate the side effects of the combination of these drugs. This study will attempt to measure the safe and effective dose of this bone marrow growth promoting factor (IL-6), document its toxicity in children, and its effectiveness in combination with Granulocyte Colony Stimulating Factor (G-CSF), in reducing the bone marrow inhibition that commonly occurs following Ifosfamide, Carboplatin, and Etoposide.